Conventional doors and windows for buildings are typically manufactured with rectangular frames which hold the door or the glass. The frames assemble from elongate members joined at distal ends. The members are known in the art as profiles. Typically the members used for windows are made from thermo-plastic materials such as extruded polyvinyl chloride and the like. The members have distal ends which define mating 45 degree angles which when joined together form a perpendicular angle for squaring a corner of the window or door frame. Frame members made from non-thermo-plastic materials, such as aluminum, have mechanical linkages which join the pair of frame members together. However, members made with thermo-plastic materials are generally joined to each other by butt welding the adjacent ends with heat.
There are existing two-head or four-head welding machines of various designs for the purpose of butt welding thermo-plastic members and forming the frame. In these devices, the members are securely clamped with special tools that attach to the machines. Each tool includes a lower support on which the lower surface of the member sits. An upper support in the tool moves vertically against the upper surface of the plastic member, thereby clamping the member in the tool. Adjacent pairs of tools then move towards each other to press distal ends of the aligned members against a heat plate for melting the distal ends of the aligned members. After a period of time, the heat plate is removed, and the tools brought together to engage the distal (now molten) ends of the members which weld or fuse together. During the welding process, melted plastic material flows around the joint.
More particularly explained, the melted plastic from the aligned ends of the members flows both outwardly and inwardly of the joint formed by the welding process. The waste material forms a plastic weld bead on the exterior and interior surfaces of the welded members. The waste bead on the interior of the welded members is not objectionable in that it strengthens the weld by providing additional thickness across the joint. However, the plastic weld bead on the exterior is unsightly for ornamental purposes as well as perhaps interfering with fitment of the window or door. Machinery however is provided to trim the waste bead from the weld joints. The joined members are placed on the machine and are passed by a blade that trims the waste bead from the exterior surfaces of the joint.
While the welding machinery described above readily joins thermo-plastic members together to form frames for windows and doors, the resulting frame incurs the additional labor and costs to trim the waste bead. The separate machine must be purchased and placed in the manufacturing process for deburring the joint, that is, trimming the waste bead from the welded joint. An operator is required to handle the frames for deburring the corners of the frame.
Accordingly, there is a need in the art for an improved tool for welding plastic members which reduces the waste material on the exterior of joints formed during the welding process. It is to such that the present invention is directed.